1. Field of the Invention
The present invention relates to a seat frame for a vehicle seat, and more particularly, to an improved seat frame including a lifter which is capable of vertically adjusting of the seat.
2. Description of the Prior Art
Conventionally, it has been a problem that the position of a driving wheel may be too high or too low for a driver according to his or her physique. In order to solve this problem, there has been proposed a seat of the type having a lifter which can adjust the height of the seat so as to suit the physique or preference of the driver.
In the above conventional seat of the type having the lifter, which is constructed by assembling the lifter between a seat frame and a seat slider on the side of a vehicle body, the lifter is provided with two symmetrical right and left link mechanisms, which are connected with each other by means of a connecting member for cooperative operation and also which are provided with a stopping operation mechanism at one side portion thereof. Therefore, the lifter cannot be installed inside the seat frame, but rather must inevitably be interposed between the lower surface side of the seat frame and the upper surface side of the seat slider.
However, since the interposition of the lifter between the seat frame and the seat slider increases the seat in thickness and thus raises the sitting position, there must be formed in the lower portion of the seat frame a recessed portion for relief of a cooperatively rotating member of the lifter link mechanism so that the seat frame can be adjacent to the seat slider. As the formation of this recess in the seat frame reduces the vertical width of the seat frame to the extent corresponding to such recessed portion and thus the strength of the seat frame is lowered accordingly, it is necessary to mount a reinforcement plate onto this recessed portion so as to compensate for the decreased strength of the seat frame. For this reason, it is difficult to reduce the thickness and weight of the seat frame.
Also, since the lifter must be assembled to the seat frame after the latter is installed, manual operations such as tightening of bolts are required, which deteriorates the efficiency of the seat assembly.